Desulfurization Sorbents Research Articles

Effects of pore structure on the performance of coal gas desulfurization sorbents

The commercially available ZnO sorbents differing in porosity and pore size distribution were used as model solids to investigate experimentally the effects of pore structure on the performance of metal oxide sorbents during H 2S removal from coal gas at high temperatures. Reactivity evolution (conversion vs time) experiments were carried out in a thermogravimetric analysis apparatus using relatively broad ranges of particle size (53–350 μm), temperature (400–600°C), and H 2S concentration (2500–10,500 ppm). The pore structure of fresh, heat-treated, and sulfided sorbents was analyzed by mercury porosimetry and nitrogen adsorption using samples prepared in fluidized or fixed-bed reactor under conditions similar to those used in the thermogravimetric analysis system. Strong effects of the pore structure of the sorbents on their performance during desulfurization were revealed by our reactivity and structure evolution data. The analysis of the experimental data showed that differences in the performance of sorbents of the same metal oxide can be explained on the basis of their different morphological characteristics provided that an appropriate model for diffusion, reaction, and structure evolution in the interior of the reacting sorbent particles is employed.

Experimental validation of a mathematical model for fixed‐bed desulfurization

AbstractPorous particles of two commercially available ZnO sorbents differing in porosity, surface area, and pore‐size distribution were reacted with H2S at 500 and 600°C in a fixed‐bed reactor. Concentration breakthrough curves were determined by analyzing the effluent of the reactor using a gas chromotograph equipped with thermal conductivity and flame photometric detectors. The pore structure of samples collected from different positions in the reactor was analyzed by mercury porosimetry and gas adsorption to determine the variation of the average structural properties of the sorbent with the length of the reactor. The obtained experimental data were used to validate a fixed‐bed desulfurization model, which employs detailed submodels for diffusion, reaction, and structure evolution in the porous sorbent particles. With the various parameters appearing in the submodels determined from independent thermogravimetric reactivity evolution experiments, the fixed‐bed desulfurization model was found to be capable of providing an excellent description of the behavior of the desulfurization sorbents in a fixed‐bed reactor.

Current Status of the ADVACATE Process for Flue Gas Desulfurization

The following report discusses current bench- and pilot-plant advances in preparation of ADVAnced siliCATE (ADVACATE) calcium silicate sorbents for flue gas desulfurization. It also discusses current bench- and pilot-plant advances in sorbent preparation. Fly ash was ground in a laboratory scale grinder prior to slurring in order to decrease the slurring time needed for the sorbent to be reactive with SO2. Reactivity of ADVACATE sorbents with SO2 in the bench-scale reactor correlated with their surface area. ADVACATE sorbents produced with ground fly ash were evaluated in the 50 cfm (85 m3/h) pilot plant providing 2 s duct residence time. ADVACATE sorbent was produced by slurrying ground fly ash (median particle size of 4.3 µm) with Ca(OH)2 at the weight ratio of 3:1 at 90°C (194°F) for 3hto yield solids with 30 weight percent of initial free moisture. When this sorbent was injected into the duct with 1500 ppm SO2 and at 11°C (20°F) approach to saturation, the measured SO2 removal was approximately 60perc...

Development of zinc ferrite sorbents for desulfurization of hot coal gas in a fluid-bed reactor

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDevelopment of zinc ferrite sorbents for desulfurization of hot coal gas in a fluid-bed reactorR. Gupta, S. K. Gangwal, and S. C. JainCite this: Energy Fuels 1992, 6, 1, 21–27Publication Date (Print):January 1, 1992Publication History Published online1 May 2002Published inissue 1 January 1992https://doi.org/10.1021/ef00031a004RIGHTS & PERMISSIONSArticle Views396Altmetric-Citations75LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (883 KB) Get e-Alerts Get e-Alerts

THE REACTIVITY AND DURABILITY OF ZINC FERRITE HIGH TEMPERATURE DESULFURIZATION SORBENTS

Cylindrical pellets of zinc ferrite high temperature desulfurization sorbent have been prepared using a number of formulation recipes and induration conditions. Physical and structural properties of the resultant sorbents were measured, and reactivity and durability screening tests were carried out using a single pellet electrobalance reactor. The formulation variables studied were ZnO to Fe2O3 ratio, Fe2O3 source, and the addition of inorganic (bentonite) and organic (methocel) binders to the sorbents. Pellet induration conditions ranged from 0.25 hours at 815°C to 4.0 hours at 1038°C. Stronger pellets having greater attrition resistance resulted when 5% bentonite was added to the formulation recipe and when the pellets were indurated at high temperature for extended times. In contrast, bentonite content was not a significant factor in determining sorbent reactivity and durability, both of which were improved by mild induration conditions. Sorbent regeneration temperature was found to be an important factor in improving reaction durability, as was the addition of 0.5% methocel to the formulation recipe. Pellets containing catalyst-grade Fe2O3 were more reactive than those containing pigment-grade Fe2O3. This effect, however, was less important than the effect of induration conditions.

Kinetics of the reactions of a zinc ferrite sorbent in high-temperature coal gas desulfurization

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the reactions of a zinc ferrite sorbent in high-temperature coal gas desulfurizationMark C. Woods, Santosh K. Gangwal, Douglas P. Harrison, and Kandaswamy JothimurugesanCite this: Ind. Eng. Chem. Res. 1991, 30, 1, 100–107Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://doi.org/10.1021/ie00049a015RIGHTS & PERMISSIONSArticle Views262Altmetric-Citations42LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (922 KB) Get e-Alerts Get e-Alerts

Characterization and long-range reactivity of zinc ferrite in high-temperature desulfurization processes

The chemical reactivity of zinc ferrire was studied experimentally to demonstrate the potential use of zinc ferrite as a sorbent in high-temperature desulfurization of coal gases. Fifty cycles of H 2 S absorption from simulated coal gas and regeneration under 4.5% oxygen were conducted in a laboratory-scale, packed-bed reactor system simulating gas compositions of a fixed-bed, air-blown gasifier and a regeneration scheme typical of a moving-bed process. Approximately 70% of the theoretical fractional conversion, as determined by thermogravimetric analysis (TGA), was maintained by the sorbent. Less than 1% residual total sulfur and total carbon were measured in the sorbent. Undesired solid phases, (e.g., metal carbides, sulfates, and elemental iron) were absent in the samples as determined by powder X-ray diffraction

Reaction between hydrogen sulfide and zinc oxide-titanium oxide sorbents. 2. Single-pellet sulfidation modeling

In the temperature range of primary interest, 650-760{degrees}C, the reaction between H{sub 2}S and a desulfurization sorbent composed of 1.5 ZnO:1.0 TiO{sub 2} (designation L-3140) can be described by a special case of the unreacted core model in which the global reaction rate is controlled by mass transfer and product layer diffusion resistances. Effective diffusivities through the product layer predicted by the random pore model show reasonable agreement with best-fit effective diffusivities determined by numerical methods. Although the magnitudes of the predicted and best-fit values differ, on average, by about 33%, the observed effects of temperature and pressure are consistent with random pore model predictions. Mass-transfer coefficients predicted by a modified Froessling equation differ from best-fit values by an average of only 15%. However, neither the effect of pressure nor the effect of temperature is adequately described. This is attributed to the fact that chemical reaction resistance is not truly negligible near the beginning of the reaction so that best-fit mass-transfer coefficients actually reflect both mass-transfer and reaction effects.

Bench‐scale testing of high‐temperature desulfurization sorbents

AbstractExtrudates of regenerable mixed‐metal oxide sorbents including zinc ferrite, copper‐modified zinc ferrite, and zinc titanate were prepared and tested for their potential to remove hydrogen sulfide (H2S) from coal gasifier gas in a high‐temperature high‐pressure (HTHP) fixed‐bed reactor. Reductions in H2S concentration from > 10,000 parts per million by volume (ppmv) to < 1 to 50 ppmv were achieved depending on sorbent, reactor temperature, and steam concentration. Zinc ferrite showed no apparent loss in capacity over 15 sulfidation‐regeneration cycles, but underwent significant strength reduction at 5% steam due to soot formation. Zinc titanate exhibited excellent strength and capacity retention at 5% steam and temperatures up to 735°C.

Treatment of hydrated lime with methanol for in-duct desulfurization sorbent improvement

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTreatment of hydrated lime with methanol for in-duct desulfurization sorbent improvementJeffrey A. Withum and Heeyoung YoonCite this: Environ. Sci. Technol. 1989, 23, 7, 821–827Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://doi.org/10.1021/es00065a010RIGHTS & PERMISSIONSArticle Views100Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

ChemInform Abstract: Comparing Regenerative SO2 Sorbents Using TG: The SRO Test.Five synthetic sorbents for regenerative desulfurization in fluidized bed combustion of coal, consisting of calcium oxide supported by Al2

AbstractO3 or TiO2, are tested for their sulfation, regeneration, and cyclic behavior using thermogravimetry.

High-temperature desulfurization using zinc ferrite: solid structural property changes

The structural property changes which accompany the reduction, sulfidation and regeneration reactions of a zinc ferrite desulfurization sorbent have been studied over the temperature range of 420–850°C. At all temperatures, sulfidation produces a decrease in the specific surface area and pore volume and an increase in the average pore radius. At sufficiently low temperatures these property changes are caused by reaction effects only, while at higher temperatures sintering and reaction combine to alter the structure. If regeneration occurs at temperatures less than or equal to 650°C, a portion of the decrease in the surface area and pore volume which accompanies sulfidation is restored and there is little difference in the global kinetics of the first and second sulfidation cycles. Regeneration at 750°C causes more severe structural changes and produces a marked deterioration in the global kinetics of the second sulfidation cycle. At the maximum regeneration temperature studied (850°C), structural property changes are so severe that the sulfided pellets cannot be completely regenerated.

石炭ガス化複合発電用乾式ガス精製システムの開発 固定床ガス精製システム

We aim to establish the technlogy of fixed bed type hot gas cleanup system for the coal gasification combined cycle power generation. We conducted test using the 2t/d process development equipment and various basic studies to obtain data for scale up the pilot plant.Main result in the technology of porous filter dust collection is favorable characteristic of pressure loss increase at the filter during collecting particles in the coal gas. We can estimate long term reliability of the porous filter from the characteristic.In the technology of fixed bed desulfurization, the bed temperature in the regeneration process has great influence on the reliability of the desulfurization sorbent. We clarified the characteristics of regeneration temperature at various regeneration condition (gas flow rate, temperature and O2 concentration et al.). We also obtained the profile of the decrease of desulfurization sorbent capacity in early desulfurization/regeneration cycles due to the increase of the residual sulfur and the change of sorbent physical properties. We use these results to establish optimum regeneration condition.We think it is necessary to estimate overall at the large sized unit for the future.

Kinetic investigation of sorbents for desulfurization of combustion gases, measured with a tubular reactor/to combination

A tubular reactor/thermobalance combination is applied for study of gas-solid interaction at high pressures and flow rates. The kinetics of sulfation and regeneration of CaO/Al 2O 3 sorbents are investigated.

Development and Pilot Plant Evaluation of Silica- Enhanced Lime Sorbents for Dry Flue Gas Desulfurization

EPA’s efforts to develop low cost, retrofitable flue gas cleaning technology include the development of highly reactive sorbents. Recent work addressing lime enhancement and testing at the bench-scale followed by evaluation of the more promising sorbents in a pilot plant are discussed here. The conversion of Ca(OH)2 with SO2 increased several-fold compared with Ca(OH)2 alone when Ca(OH)2 was slurrled with fly ash first and later exposed to SO2 in a laboratory packed bed reactor. Ca(OH)2 enhancement increased with the increased fly ash amount. Dlatomaceous earths were very effective reactivity promoters of lime-based sorbents. Differential scanning calorimetry of the promoted sorbents revealed the formation of a new phase (calcium silicate hydrates) after hydration, which may be the basis for the observed Improved SO2 capture. Fly ash/lime and diatomaceous earth/lime sorbents were tested in a 100 m3/h pilot facility incorporating a gas humidifier, a sorbent duct injection system, and a baghouse. The inlet SO2 concentration range was 1000-2500 ppm. With once-through dry sorbent injection into the humidified flue gas [approach to saturation 10–20°C (18–36°F) in the baghouse], the total SO2 removal ranged from 50 to 90 percent for a stoichiometric ratio of 1 to 2. Recycling the collected solids resulted in a total lime utilization exceeding 80–90 percent. Increased lime utilization was also investigated by the use of additives.

Calcium silicates: A new class of highly regenerative sorbents for hot gas desulfurization

AbstractA study has been conducted on the utilization of calcium silicates and the silica supported lime as regenerative sorbents for desulfurization of hot combustion gases. Except for γ‐Ca2SiO4 and Ca3SiO5, all the calcium silicates and the silica supported calcium oxide are equally or more reactive than calcium oxide, and the regeneration rates of these sorbents are substantially higher than that of calcium oxide. There was no tendency of decaying of the reactivity after eight cycles of sorption and regeneration.